Laser assisted cataract surgery

ABSTRACT

Laser assisted cataract surgery methods and devices utilize one or more treatment laser beams to create a shaped opening in the anterior lens capsule of the eye when performing a capsulorrhexis procedure. A light absorbing agent may be applied to the anterior lens capsule to facilitate laser thermal separation of tissue along a treatment beam path on the lens capsule. Relative or absolute reflectance from the eye, and optionally from a surgical contact lens, may be measured to confirm and optionally quantify the presence of the light absorbing agent, before the treatment beam is applied. Such measurements may be used to determine that sufficient light absorbing agent is present in the lens capsule so that transmission of the treatment beam through the capsule will be below a predetermined threshold deemed safe for the retina and other interior portions of the eye, and may also be used to determine that sufficient light absorbing agent is present to result in complete laser thermal separation of the anterior capsule along the treatment beam path. Visualization patterns produced with one or more target laser beams may be projected onto the lens capsule tissue to aid in the capsulorrhexis procedure. In addition or alternatively, virtual visualization patterns may presented on a display integrated with a laser assisted cataract surgery device to aid in the procedure. The visual axis of the eye may be determined, during surgery for example, with a laser beam on which the patient is fixated. The orientation of a toric IOL may be assessed during or after placement by observing the reflection from the back of the eye of a laser beam on which the patient is fixated. The devices disclosed herein may be attached to or integrated with microscopes.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application is a Continuation of International PatentApplication No. PCT/US2015/018158 titled “Laser Assisted CataractSurgery” and filed Feb. 27, 2015. International Patent Application No.PCT/US2015/018158 claims benefit of priority from U.S. patentapplication Ser. No. 14/193,592 titled “Laser Assisted Cataract Surgery”filed Feb. 28, 2014, U.S. patent application Ser. No. 14/193,630 titled“Laser Assisted Cataract Surgery” filed Feb. 28, 2014, U.S. patentapplication Ser. No. 14/193,671 titled “Laser Assisted Cataract Surgery”filed Feb. 28, 2014, U.S. patent application Ser. No. 14/193,716 titled“Laser Assisted Cataract Surgery” filed Feb. 28, 2014, U.S. ProvisionalPatent Application No. 61/975,506 titled “Laser Assisted CataractSurgery” filed Apr. 4, 2014, and U.S. Provisional Patent Application No.62/047,373 titled “Laser Assisted Cataract Surgery and filed Sep. 8,2014. Each of the patent applications listed above is incorporatedherein by reference in its entirety.

FIELD OF THE INVENTION

The invention relates generally to laser assisted ophthalmic surgery,and more particularly to methods and devices using one or more lasers inperforming a capsulorrhexis.

BACKGROUND

Cataracts are a common cause of poor vision and are the leading cause ofblindness. There are at least 100M eyes with cataracts causing visualacuity of less than 6/60 in meters (or 20/200 in feet). Cataractextraction is the most commonly performed surgical procedure in theworld with estimates of over 22 million cases worldwide and over 3million cases being performed annually in North America. Generally,there are two types of cataract surgery: small incision cataract surgerywith phacoemulsification, and extra-capsular cataract extraction.

In small incision cataract surgery with phacoemulsification, the morecommon approach, about a 2 millimeter (mm) incision is made in thecornea and the opacified natural lens is removed with irrigation,aspiration, and phacoemulsification while leaving the elastic lenscapsule intact to allow implantation and retention of an intraocularlens (IOL). Currently, extra-capsular cataract extraction surgery is amore invasive procedure and is performed in the developing countrieswhere there are fewer resources. In this procedure a large incision of 6mm or more is made in the sclera, and the complete opacified naturallens is removed.

One of the more critical components of both of these surgical proceduresis the capsulorrhexis (which is also referred to as the capsulotomy),which is the incision in the lens capsule made to permit removal of thelens nucleus and cortex. The lens capsule is a transparent, homogeneousbasement membrane that comprises collagen. It has elastic propertieswithout being composed of elastic fibers. The capsule has a smoothsurface contour except at its equator where zonules attach.

Typically the capsulorrhexis creates a symmetric circular incision,centered about the visual axis and sized appropriately for the IOL andthe patient's condition. The mechanical integrity around the newlyformed incision edge needs to be sufficient to withstand the forcesexperienced during cataract extraction and IOL implantation.Postoperatively, the newly formed capsule rim hardens and the openingcontracts, providing further strength and structural support for the IOLto prevent dislocation and misalignment.

The current standard of care for capsulorrhexis is ContinuousCurvilinear Capsulorrhexis (CCC). The concept of CCC is to provide asmooth continuous circular opening through the anterior lens capsule forphacoemulsification and insertion of the intraocular lens, minimizingthe risk of complications including errant tears and extensions.Currently, the capsulorrhexis is performed manually utilizing forceps ora needle. This technique depends on applying a shear force andminimizing in-plane stretching forces to manually tear the incision. Onecomplication that may develop when performing a capsulorrhexis in thismanner is an errant tear. Errant tears are radial rips and extensions ofthe capsulorrhexis towards the capsule equator. If an errant tearencounters a zonular attachment the tear may be directed out to thecapsular fornix and possibly through to the posterior of the capsule.Posterior capsule tears facilitate the nucleus being “dropped” into theposterior chamber, resulting in further complications.

Further problems that may develop in capsulorrhexis are related toinability of the surgeon to adequately visualize the capsule due to lackof red reflex (reddish reflection of light from the retina), to grasp itwith sufficient security, or to tear a smooth symmetric circular openingof the appropriate size. Additional difficulties may relate tomaintenance of the anterior chamber depth after initial opening, smallsize of the pupil, or the absence of a red reflex due to the lensopacity. Additional complications arise in older patients with weakzonules and very young children that have very soft and elasticcapsules, which are very difficult to mechanically rupture.

Following cataract surgery there is a rapid 1-2 day response where thecapsule hardens and capsule contraction starts. This contractioncontinues over a 4-6 week period where fibrosis of the capsulorrhexisand IOL optic interface and of the IOL haptic and capsule interfacesalso occurs. Even beyond one year the capsule continues to contract to alesser degree. Thus positioning the capsulorrhexis is a critical factorin the long-term success.

Accordingly, there is a need in the art to provide new ophthalmicmethods, techniques and devices to advance the standard of care forcapsulorrhexis.

SUMMARY

This specification discloses laser assisted ophthalmic surgery methodsand devices.

In one aspect, a device for creating an opening in the anterior lenscapsule of the eye comprises a scanning treatment laser beam having aprogrammed scan profile for a predetermined treatment pattern that formsa closed curve at the anterior lens capsule. The treatment laser has awavelength selected to be strongly absorbed at the anterior lens capsuleand a power selected to cause thermal denaturing of collagen in theanterior lens capsule resulting in thermal tissue separation along theclosed curve without ablating anterior lens capsule tissue. The devicealso comprises a scanning visualization laser beam having a programmedscan profile for a predetermined visualization pattern at the anteriorlens capsule and a wavelength in the visible spectrum.

The visualization pattern differs from the treatment pattern in size andgeometry. At least a portion of the visualization pattern may, forexample, indicate desired boundaries of the opening to be created in theanterior lens capsule and thereby facilitate aligning the treatmentpattern on the anterior lens capsule. Typically, the desired boundariesof the opening differ in location from the closed curve of the treatmentpattern as a result of contraction of anterior lens capsule tissueadjacent to the closed curve during and after thermal tissue separation.Alternatively, or in addition, at least a portion of the visualizationpattern may correspond to one or more anatomical features of the eye,and thereby facilitate aligning the treatment pattern with respect tothose anatomical features.

In another aspect, a device for creating an opening in the anterior lenscapsule of the eye comprises a treatment laser beam and atwo-dimensional scanner on which the treatment laser beam is incident.The scanner has a programmed scan profile for a predetermined treatmentpattern in which the treatment laser beam is scanned to form a closedcurve at the anterior lens capsule. The device comprises a lenspositioned to focus the treatment laser beam to a waist at the anteriorlens capsule, with the treatment beam expanding from its waist to bedefocused on the retina of the eye. The treatment pattern passes througha treatment pattern invariant and/or a treatment pattern waist betweenthe lens and the eye. The treatment laser beam has a wavelength selectedto be strongly absorbed at the anterior lens capsule and a powerselected to cause thermal denaturing of collagen in the anterior lenscapsule resulting in thermal tissue separation along the closed curve ofthe treatment pattern without ablating anterior lens capsule tissue.

The treatment pattern may diverge in the eye and consequently beexpanded in size and area on the retina compared to its size and area atthe anterior lens capsule. As a result, the treatment pattern may avoidthe fovea on the retina.

In another aspect, a device for creating an opening in the anterior lenscapsule of the eye comprises a continuous wave scanning treatment laserbeam having a programmed scan profile for a predetermined treatmentpattern forming a closed curve at the anterior lens capsule in a singlepass. The treatment laser has a wavelength selected to be stronglyabsorbed at the anterior lens capsule, and a power selected to causethermal denaturing of collagen in the anterior lens capsule resulting inthermal tissue separation along the closed curve without ablatinganterior lens capsule tissue. At the beginning of the treatment patternthe power of the treatment laser ramps up from about zero to about 90%of its full power during a period of about 5 milliseconds to about 200milliseconds. This ramp-up may minimize the likelihood of the capsuletearing at the starting point of the treatment pattern by allowing thetissue near the starting point of the pattern to initially stretchwithout separating, thereby reducing the shear stress/tension at thestart of the pattern, and/or by avoiding or minimizing local shock wavesin the fluid adjacent to the target tissue that might otherwise begenerated by the growth and collapse of one or more vapor bubblesaccompanying a faster thermal turn-on.

In another aspect, a device for creating an opening in the anterior lenscapsule of the eye comprises a treatment laser beam and atwo-dimensional scanner on which the treatment laser beam is incident.The scanner has a programmed scan profile for a predetermined treatmentpattern in which the treatment laser beam is scanned to form a closedcurve at the anterior lens capsule. The device comprises a lenspositioned to focus the treatment laser beam to a waist at the anteriorlens capsule, with the treatment laser beam expanding from its waist tobe defocused on the retina of the eye. The treatment laser beam has awavelength selected to be strongly absorbed at the anterior lens capsuleand a power selected to cause thermal denaturing of collagen in theanterior lens capsule resulting in thermal tissue separation along theclosed curve of the treatment pattern without ablating anterior lenscapsule tissue. The device also comprises a first visible lightvisualization laser beam sharing an optical path with the treatmentlaser beam, and a second visible light visualization laser beamintersecting the first visualization laser beam at or approximately atthe waist of the treatment laser beam.

The first visualization laser beam and the second visualization laserbeam may be produced, for example, from a single visible light laserbeam incident on the scanner by dithering the scanner between theoptical path of the first visualization laser beam and the optical pathof the second visualization laser beam.

In another aspect, virtual visualization patterns may be presented on adisplay and overlaid with a view of the anterior lens capsule to aid inthe ophthalmic surgical procedures described herein. Such virtualvisualization patterns may be used instead of, or in addition to, theprojected visualization patterns described herein.

In another aspect, the visual axis of the patient's eye may bedetermined before or during an ophthalmic surgical procedure by havingthe patient fixate on (look directly into) a low power laser beam.Optionally, the laser beam may blink at a frequency perceptible by thepatient to facilitate fixation on the beam.

In another aspect, the orientation of a toric IOL implanted in apatient's eye may be assessed by having the patient fixate on a lowpower laser beam and observing a reflection of the laser beam from theback of the patient's eye through the toric IOL.

In another aspect, relative or absolute reflectance from an eye may bemeasured to confirm and optionally quantify the presence of a lightabsorbing agent in or on the anterior lens capsule. Such measurementsmay be used to determine that sufficient light absorbing agent ispresent in the lens capsule so that transmission of the treatment beamthrough the capsule will be below a predetermined threshold deemed safefor the retina and other interior portions of the eye. Such measurementsmay also be used to determine that sufficient light absorbing agent ispresent to result in complete laser thermal separation of the anteriorcapsule along the treatment beam path, when the selected/preprogrammedtreatment beam parameters are applied. These determinations may utilizea correlation between transmission of the treatment beam through thecapsule and reflectance from the capsule at the treatment wavelength oranother wavelength. Additionally, or alternatively, the reflectancemeasurements and their correlation with transmission of the treatmentbeam through the lens capsule may be used to optimize treatmentparameters such as, for example, treatment beam power, spot diameter,and scanning speed.

These and other embodiments, features and advantages of the presentinvention will become more apparent to those skilled in the art whentaken with reference to the following more detailed description of theinvention in conjunction with the accompanying drawings that are firstbriefly described.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a transverse plane view of some parts of an eye (lenscapsule 110, dilated iris 140, cornea 160, anterior chamber 170, andpupil 190), the natural crystalline lens location and the intendedlocation of an implanted intraocular lens 120, a light absorbing agent130, and a treatment light beam 150 to be used in an example of thecapsulorrhexis procedure described herein.

FIG. 2 shows a side view of the lens capsule 110 of FIG. 1 wherein lenscapsule 110 has been separated at location 210 into two parts, e.g. anexterior part 110-E and an interior part 110-I, by a laser based methodas described herein. This figure also shows the contracted and shrunkenends 220-E and 220-I bordering the separation.

FIGS. 3A-3H show a view from the anterior direction of a lens capsuleillustrating an example “Interior-Closed-Curve-Interior” treatmentpattern in which the treatment laser beam is directed along apredetermined closed curve 310.

FIGS. 4A-4G show a view from the anterior direction of a lens capsuleillustrating an example “Interior-Closed-Curve” treatment pattern inwhich the treatment laser beam is directed along a predetermined closedcurve 410.

FIGS. 5A-5H show a view from the anterior direction of a lens capsuleillustrating an example “Interior-Closed-Curve-Overlap” treatmentpattern in which the treatment laser beam is directed along apredetermined closed curve 410.

FIGS. 6A-6G show a view from the anterior direction of a lens capsuleillustrating an example “Closed-Curve-Overlap” treatment pattern inwhich the treatment laser beam is directed along a predetermined closedcurve 610.

FIGS. 7A-7H show a view from the anterior direction of a lens capsuleillustrating an example “Interior-Closed-Curve-Overlap-Interior”treatment pattern in which the treatment laser beam is directed along apredetermined closed curve 710.

FIG. 8 shows a view of the eye with the limbus 810, iris 140, interiorboundary of the iris 820, pupil 190, and a visualization patterncomprising a predetermined closed curve and at least three dots 830 thatare used to assist in locating the position of the desiredcapsulorrhexis.

FIGS. 9A-9B show views of the eye including the limbus 810, iris 140,and pupil 190 on which are superimposed two additional examplevisualization patterns, each of which comprises two circles or closedcurves, 910 and 920.

FIG. 10A-10B show views of the eye including the limbus 810, iris 140,and pupil 190 on which are superimposed two additional examplevisualization patterns, each of which comprises two circles or closedcurves 1010 and 1020 with dots 1030 on the curves.

FIGS. 11A-11B show views of the eye including the limbus 810, iris 140,and pupil 190 on which are superimposed two additional examplevisualization patterns, each of which comprises a cross-hair and twocircles or closed curves with dots on the curves.

FIGS. 12A-12L show additional visualization patterns each of which maycomprise a combination of closed curves, 1205, 1210, 1220, 1260, dots1230 on the curves, and a cross-hair 1240.

FIGS. 13A-13B show an example of an elliptical rhexis with a major and aminor axis and a rotation angle. FIGS. 13C-13D show two examples ofvisualization patterns that may be used with the elliptical rhexis ofFIGS. 13A-13B. Each pattern comprises a circular outer closed curve andan elliptical inner closed curve.

FIG. 14 shows a view of the eye with the limbus 810, iris 140, interiorboundary of the iris 820, dilated pupil 190, a visualization patterncomprising a cross-hair 1440 and two circles 1460 with dots 1430 on thecurves, and a treatment beam pattern for a circular rhexis 1490.

FIG. 15 shows a view of the eye with the limbus 810, iris 140, interiorboundary of the iris 820, and dilated pupil 190, a visualization patterncomprising a cross-hair 1540 and outer circle 1520 with dots 1530, andan inner ellipse 1510 with dots 1530, and a treatment beam pattern foran elliptical rhexis 1590.

FIG. 16 shows a plot of power versus time for an example treatment laseroutput pulse delivered to the collagen containing tissue that may beused in the devices and methods described herein.

FIG. 17 illustrates the dependence of the power as a function ofirradiated area required to achieve thermal separation of the anteriorcapsule in the eye. The power has a low dependence at the smaller areas,and as the area increases there is a greater dependence of power on theirradiated area.

FIGS. 18A-18C show three example ray traces of a scanned laser beamdirected into an eye through the cornea and the lens and onto theretina, and the resulting projection of the scanned laser beam on theretina. FIG. 18A shows a ray trace in the absence of a surgical contactlens, and FIGS. 18B-18C show ray traces in the presence of two differentsurgical contact lenses.

FIG. 19 shows elements of an example device that may be used to scanlaser beams in an eye to perform ophthalmic surgeries as describedherein.

FIG. 20 shows the example device of FIG. 19 externally integrated with amicroscope as an attachment to the microscope.

FIG. 21 shows the example device of FIG. 19 internally integrated with amicroscope, with a shared illumination mirror and microscope objective.

FIG. 22 shows another example device similar to that of FIG. 19 but alsoincluding optical elements facilitating depth alignment with respect tothe tissue to be treated.

FIGS. 23A-23C show views of two superimposed visualization patternsproduced by the device of FIG. 22 as the depth alignment of the deviceis adjusted.

FIGS. 24A-24B show two example foot-operable controls that may be usedto control the device of FIG. 22.

FIG. 25 shows an example device that may be used to scan laser beams inan eye to perform ophthalmic surgery, similar to the devices of FIGS.19-22, with the device externally integrated with a microscope having adisplay on which a virtual visualization pattern may be overlaid with aview through the microscope of the surgical field.

FIG. 26A shows an oscilloscope trace for a measurement of thetransmission of a treatment laser beam, as a function of time, throughan anterior lens capsule treated with a light absorbing agent.

FIG. 26B shows the data of FIG. 26A presented in a plot of transmissionversus time.

FIG. 27A and FIG. 27B show, respectively, example images and a plot ofrelative reflectance that illustrate decreasing reflectance of broadband illumination from a lens capsule as the amount of a light absorbingagent applied to the capsule is increased.

FIG. 28A and FIG. 28B show, respectively, example images and a plot ofrelative reflectance that illustrate a decreasing reflectance of narrowband (red) visualization laser illumination from a lens capsule as theamount of a light absorbing agent applied to the capsule is increased.

FIG. 29 shows plots of transmission at a treatment beam wavelength, andreflectance at another wavelength, through an anterior lens capsuletreated with increasing amounts of a light absorbing agent.

FIG. 30 shows a plot illustrating the correlation between thetransmission and reflectance curves shown in FIG. 29.

DETAILED DESCRIPTION

The following detailed description should be read with reference to thedrawings, in which identical reference numbers refer to like elementsthroughout the different figures. The drawings, which are notnecessarily to scale, depict selective embodiments and are not intendedto limit the scope of the invention. The detailed descriptionillustrates by way of example, not by way of limitation, the principlesof the invention. This description will clearly enable one skilled inthe art to make and use the invention, and describes severalembodiments, adaptations, variations, alternatives and uses of theinvention, including what is presently believed to be the best mode ofcarrying out the invention. As used in this specification and theappended claims, the singular forms “a,” “an,” and “the” include pluralreferents unless the context clearly indicates otherwise.

As described in more detail below, this specification disclosesophthalmic surgery methods and devices that utilize one or moretreatment laser beams to create a shaped opening in the anterior lenscapsule of the eye when performing a capsulorrhexis procedure. In theprocedure, a light absorbing agent may optionally be added onto or intothe lens capsule tissue, and the treatment laser wavelength selected tobe strongly absorbed by the light absorbing agent. Alternatively, thetreatment laser wavelength may be selected to be absorbed or stronglyabsorbed by the tissue itself, in which case no additional lightabsorbing agent need be used. In either case, as used herein the phrase“strongly absorbed” is intended to mean that transmission of thetreatment beam through the tissue to be treated (e.g., the anterior lenscapsule) is less than about 65%, or less than about 40%, or less thanabout 30%, or less than about 20%, or less than about 15%, or less thanabout 10%. For example, in some variations the treatment beam isstrongly absorbed such that transmission through the tissue to betreated is about 11%+/−3%. The treatment laser beam is directed at thelens capsule tissue along a predetermined closed curve to cause athermal effect in the tissue resulting in separation of the tissue alongthe laser beam path. The predetermined closed curve may have, forexample, a circular or elliptical shape. Any other suitable shape forthe closed curve may also be used. Typically, the shape is selected toreduce the likelihood of tears developing during cataract surgery, onthe edge of the separated edge of the tissue that is formed exterior tothe closed curve. Visualization patterns produced with one or moretarget laser beams may be projected onto the lens capsule tissue to aidin the procedure.

General aspects of these methods and devices may be better understoodwith reference to FIG. 1 and FIG. 2. FIG. 1 shows, in a transverse planeview of an eye (including lens capsule 110, dilated iris 140, cornea160, anterior chamber 170, and pupil 190), the intended location of anintraocular lens 120 to be implanted after a capsulorrhexis procedure.In the illustrated example, a light absorbing agent 130 is added into oronto a layer of the anterior lens capsule 110. This agent may be abiocompatible agent (e.g. Indocyanine green or Trypan Blue), a dye,pigment, a nanoparticle, a carbon particle, or any other suitable lightabsorbing agent. The light absorbing agent may be Trypan Blue, otherVital Dyes, or Indocyanine Green, for example. Subsequently, a lightbeam 150, e.g. a laser beam, is directed along a closed curve path onthe anterior lens capsule. The directed light beam is absorbed by thelight absorbing agent to deposit thermal energy in and cause a localthermal effect on the anterior lens capsule to yield a capsulorrhexis.

Referring now to FIG. 2, generally the wavelength, power, speed of lightbeam movement along the closed curve, and spot size on the treatedtissue are selected so that the light beam can be absorbed by the lightabsorbing agent to deposit sufficient thermal energy adjacent to or atthe anterior lens capsule to cause a mechanical separation 210 in theanterior lens capsule. The laser beam parameters are typically selectedto avoid ablation of the tissue, and the mechanical separation isbelieved to result instead from thermal denaturing of collagen in thetissue (in which, for example, the collagen transitions from acrystalline helical structure to an amorphous structure). The denaturedcollagen shrinks and contracts to form thickened rims 220-E and 220-Ibordering the separation forming the capsulorrhexis. Advantageously,these rims may be more elastic and resistant to tearing than theoriginal membrane.

For clarity and convenience, various features and aspects of theinventive methods and devices are described below under separatelylabeled headings. This organization of the description is not meant tobe limiting. Variations of the methods and devices described herein mayinclude or employ any suitable combination of aspects or featuresdescribed under the separate headings.

Treatment Beam Patterns

FIGS. 3A-3H illustrate an example “Interior-Closed-Curve-Interior”treatment pattern in which the treatment laser beam is directed along apredetermined closed curve 310. The treatment pattern starts interior tothe closed curve, progresses around the closed curve, then terminatesinterior to the closed curve. Although illustrated as clockwise, thispattern may also be counterclockwise. Dashed line 310 of FIG. 3Arepresents the complete pattern. The dot 320 in FIG. 3B indicates thestart point of the pattern on the interior of the closed curve, andFIGS. 3C-3H illustrate the progression of the pattern with a solid line330 at subsequent time intervals through the delivery of the pattern.Dot 340 in FIG. 3H indicates the end point of the treatment pattern onthe interior of the closed curve. Locating the start and end points ofthe procedure on the interior of the closed curve (in material whichwill be removed from the eye) helps prevent irregularities in the shapeof the curve that might promote tearing of the rim of the remaininganterior lens capsule located exterior to the closed curve.

FIGS. 4A-4G illustrate an example “Interior-Closed-Curve” treatmentpattern in which the treatment laser beam is directed along apredetermined closed curve 410. The treatment pattern starts interior tothe closed curve, progresses around the closed curve, and thenterminates on the closed curve. Although illustrated as clockwise, thispattern may also be counterclockwise. Dashed line 310 of FIG. 4Arepresents the complete pattern. The dot 320 in FIG. 4B indicates thestart point of the pattern on the interior of the closed curve, andFIGS. 4C-4G illustrate the progression of the pattern with a solid line330 at subsequent time intervals through the delivery of the pattern.Dot 440 in FIG. 4G indicates the end point of the treatment pattern onthe closed curve.

FIGS. 5A-5H illustrate an example “Interior-Closed-Curve-Overlap”treatment pattern in which the treatment laser beam is directed along apredetermined closed curve 410. The treatment pattern starts in theinterior region of the closed curve, progresses around the closed curvewith a region of overlap on the closed curve, and then terminates on theclosed curve. Although illustrated as clockwise, this pattern may alsobe counterclockwise. Dashed line 410 of FIG. 5A represents the completepattern. The dot 320 in FIG. 5B indicates the start point of the patternon the interior of the closed curve, and FIGS. 5C-5H illustrate theprogression of the pattern with a solid line 330 at subsequent timeintervals through the delivery of the pattern. Dot 540 in FIG. 5Hindicates the end point of the treatment pattern on the closed curve,where the region 550 on the closed curve experiences treatment exposureof the laser near the beginning of the pattern, and again towards thelater part of the pattern delivery, i.e., it is the overlap region.

FIGS. 6A-6G illustrate an example “Closed-Curve-Overlap” treatmentpattern in which the treatment laser beam is directed along apredetermined closed curve 610. The treatment pattern starts on theclosed curve, progresses around the closed curve with a region ofoverlap on the closed curve, and then terminates on the closed curve.Although illustrated as counterclockwise, this pattern may also beclockwise. Dashed line 610 of FIG. 6A represents the complete pattern.Dot 620 in FIG. 6B indicates the start point on the closed curve, andFIGS. 6C-6G illustrate the progression of the pattern with a solid line330 at subsequent time intervals through the delivery of the pattern.Dot 540 in FIG. 6G indicates the end point of the treatment pattern onthe closed curve, where the region 550 on the closed curve experiencestreatment exposure of the laser near the beginning of the pattern, andagain towards the later part of the pattern delivery, i.e., it is theoverlap region.

FIGS. 7A-7H illustrate an example“Interior-Closed-Curve-Overlap-Interior” treatment pattern in which thetreatment laser beam is directed along a predetermined closed curve 710.The treatment pattern starts interior to the closed curve, thenprogresses around the closed curve with a region of overlap on theclosed curve, and then terminates on the interior of the closed curve.Although illustrated as clockwise, this pattern may also becounterclockwise. Dashed line 710 of FIG. 7A represents the completepattern. Dot 320 in FIG. 7B indicates the start point on the interior ofthe closed curve, and FIGS. 7C-7H illustrate the progression of thepattern with a solid line 330 at subsequent time intervals through thedelivery of the pattern. As shown in FIGS. 7G-7H, region 550 on theclosed curve experiences treatment exposure of the laser near thebeginning of the pattern, and again towards the later part of thepattern delivery, i.e., it is the overlap region. Dot 340 in FIG. 7Hindicates the end point of the treatment pattern on the interior of theclosed curve.

Any other suitable treatment beam patterns may also be used. One or moretreatment beam pattern shapes may be preprogrammed into a lasercapsulorrhexis device (described in more detail below) by themanufacturer, for example. At or prior to the time of treatment anoperator may then, for example, select the size (e.g., diameter) andshape of the closed curve defining the treatment pattern, or of thedesired rhexis to be produced by the closed curve of the treatmentpattern.

Visualization/Target Patterns

As noted above, visualization patterns produced with one or more laserbeams, which typically differ in wavelength from the treatment beam, maybe projected onto the lens capsule tissue to aid in the treatmentprocedure. The shape and diameter of the visualization pattern maydiffer from that of the treatment beam pattern. Although thevisualization pattern or portions of the visualization pattern mayoverlie the closed curve of the treatment pattern to indicate at leastportions of the path to be taken by the treatment beam, this is notrequired. Instead, or in addition, at least part of the visualizationpattern may overlie the intended location of the outer rim of theopening that will be produced by the tissue-separating treatment beam,or otherwise indicate the desired outcome of the treatment. The locationof that outer rim typically differs from and is of larger diameter thanthe closed curve of the treatment beam pattern for two reasons: (i) thelens capsule tissue is under tension when in the eye (very much like adrum skin), so as the tissue along the closed curve is separated theexterior portion is under tension and pulled peripherally, thusenlarging the diameter; (ii) the mechanism of action for the treatmentlaser is to locally heat the irradiated anterior capsule on a closedcurve, this heating tends to cause the collagen tissue to contract,shrink, and separate exteriorly and interiorly away from the heatedclosed curve. Alternatively, or in addition, at least part of thevisualization pattern may correspond to one or more particularanatomical features of the eye. This may facilitate centering of thevisualization pattern (and thus the treatment beam pattern) on theanatomy of the eye, or otherwise facilitate aiming the visualization andtreatment beams. The visualization pattern may optionally include across-hair.

FIG. 8 illustrates an example visualization pattern 830 comprising aclosed curve and at least three dots that may be used to assist inlocating the desired location for a capsulorrhexis. The figure alsoidentifies the limbus 810, iris 140, interior boundary of the iris 820,and pupil 190 of the eye to be treated.

FIGS. 9A-9B each show a view of an eye including the limbus 810, iris140, and pupil 190 onto which is projected an example visualizationpattern 900 comprising two concentric circles or closed curves 910 and920. The inner circle or closed curve 910 represents the size andlocation of the desired opening in the anterior capsulorrhexis. Theouter circle 920, which may be sized independently of the inner circlesize, may be used to center the capsulorrhexis on the limbus asillustrated in FIG. 9A. Alternatively, the outside circle may be sizedto allow the centering on the interior boundary of the dilated pupil, asrepresented in FIG. 9B.

FIGS. 10A-10B each show a view of an eye including the limbus 810, iris140, and pupil 190 onto which is projected an example visualizationpattern 1000 comprising two concentric circles or closed curves 1010 and1020 with dots 1030 on the curves. The combination of straight and/orcurved lines and dots provides a pattern easily focused on the targettissue. The lines are produced by moving the visualization beam alongthe desired pattern. The dots are produced by dwelling the visualizationbeam for longer periods at the dot locations in the scan pattern. Thedots may provide enhanced visualization on the target tissue becausethey are more intense than the lines. The inner circle or closed curve1010 represents the size and location of the desired opening in theanterior capsulorrhexis. The outer circle 1020, which may be sizedindependently of the inner circle size, may be used to center thecapsulorrhexis on the limbus as illustrated in FIG. 10A. Alternatively,the outside circle may be sized to facilitate centering on the interiorboundary of the dilated pupil, as represented in FIG. 10B.

FIGS. 11A-11B each show a view of an eye including the limbus 810, iris140, and pupil 190 onto which is projected an example visualizationpattern 1100 comprising two concentric circles or closed curves 1110 and1120 with dots 1130 on the curves and a cross hair 1140. The combinationof lines and dots provides a pattern easily focused on the targettissue. The lines are produced by moving the visualization beam alongthe desired pattern. The dots are produced by dwelling the visualizationbeam for longer periods at the dot locations in the scan pattern. Thedots may provide enhanced visualization on the target tissue becausethey are more intense than the lines. The inner circle or closed curve1110 represents the size and location of the desired opening in theanterior capsulorrhexis. The outer circle 1120, which may be sizedindependently of the inner circle size, may be used to center thecapsulorrhexis on the limbus as illustrated in FIG. 11A. Alternatively,the outside circle may be sized to facilitate centering on the interiorboundary of the dilated pupil, as represented in FIG. 11B. The additionof the cross hair further enhances the ability to focus and center thevisualization pattern.

FIGS. 12A-12L show additional visualization patterns each of which maycomprise a combination of inner 1205, 1210 and outer 1220 closed curves,dots 1230 on the curves, dots 1230 not on curves, a cross-hair 1240,dashed arcs 1250, and/or straight-line segments 1260 forming closedcurves. Generally, the closed visualization curves shown in these andother figures may be formed from straight line segments, which may beeasier to program and/or easier to generate than curved arcs.

FIGS. 13A-13B show an example of an elliptical rhexis 1300 with a majorand a minor axis and a rotation angle. FIGS. 13C-13D show two examplesof visualization patterns that may be used with the elliptical rhexis ofFIGS. 13A-13B. Each pattern comprises a circular outer closed curve andan elliptical inner closed curve (1320 and 1310, respectively, in FIG.13C), dots 1330 on the curves, and a cross hair 1340. In FIG. 13D theclosed curves are formed with straight-line segments 1360. Theelliptical inner closed curves represent the size and location of thedesired opening in the anterior capsulorrhexis. The outer circles, whichmay be sized independently of the inner ellipse size, may be used tocenter the capsulorrhexis on the limbus, for example.

FIG. 14 shows a view of an eye including the limbus 810, iris 140,interior boundary of the iris 820, and pupil 190 onto which is projectedan example visualization pattern comprising two concentric closedcircles or curves with dots 1430 on the curves and a cross hair 1440.The closed curves are formed from straight-line segments 1460. The innercircle or closed curve represents the size and location of the desiredopening in the anterior capsulorrhexis. The outer circle, which may besized independently of the inner circle, may be used to center thecapsulorrhexis on the limbus as illustrated. Alternatively, the outercircle may be sized to facilitate centering on the interior boundary ofthe dilated pupil. This figure also shows the treatment beam pattern1490 for a desired circular rhexis. Treatment beam pattern 1490 differsfrom and is of a smaller diameter than the visualization pattern innerclosed circle.

FIG. 15 shows a view of an eye including the limbus 810, iris 140,interior boundary of the iris 820, and pupil 190 onto which is projectedan example visualization pattern comprising an outer circular closedcurve 1520 and an inner elliptical closed curve 1510, dots 1530 on thecurves, and a cross hair 1540. The elliptical inner closed curvesrepresent the size and location of the desired opening in the anteriorcapsule. The outer circle, which may be sized independently of the innerellipse, may be used to center the capsulorrhexis on the limbus asillustrated. Alternatively, the outer circle may be sized to facilitatecentering on the interior boundary of the dilated pupil. This figurealso shows the treatment beam pattern 1590 for a desired ellipticalrhexis. Treatment beam pattern 1590 differs from and is smaller than thevisualization pattern inner ellipse.

Any other suitable visualization beam patterns may also be used. One ormore visualization beam pattern shapes may be preprogrammed into a lasercapsulorrhexis device (described in more detail below) by themanufacturer, for example. At or prior to the time of treatment anoperator may then, for example, select a pattern size and shape to beused to guide the treatment.

The location of the visual axis relative to center on the limbus ordilated pupil may also be measured on a separate diagnostic device. Theoffset data from center may then also be manually or automatically inputinto the laser capsulorrhexis device. In such cases, the visualizationpattern may be arranged so that when an exterior portion of thevisualization pattern (e.g., a circle) is positioned or centered on theeye anatomy of the limbus or dilated pupil, the center of an interiorportion (e.g., a circle or ellipse) of the visualization pattern isoffset from the center of the limbus or dilated pupil to lie on thevisual axis. The center of the closed curve of the treatment pattern maybe correspondingly offset from the center of the limbus or dilatedpupil, so that the central circle or ellipse of the visualizationpattern indicates the perimeter of the desired rhexis.

The visualization pattern laser beam may have any suitable wavelength inthe visible spectrum. The visualization beam may be scanned across thetissue to be treated at, for example, a speed greater than about 450mm/second, though it may also dwell to form dots or other brighterfeatures in the visualization pattern. Any suitable scanning speeds maybe used. The diameter of the visualization light beam on the tissuesurface may be, for example, about 50 to about 600 microns. Thevisualization laser beam power at the tissue may be, for example, lessthan about 10 mW or less than about 1 mW when the beam is dwelling on adot in the visualization pattern. When the visualization beam isscanning its power may be, for example, less than about 30 mW. Generallythe power and the wavelength of the laser beam are selected to provide asufficiently visible visualization pattern without significantlydepleting any absorbing agent that has been deposited on the tissue tofacilitate treatment.

Treatment Beam and Scanning Parameters

Generally, parameters characterizing the treatment laser beam and thetreatment beam scanning procedure are selected to provide the desiredlaser induced thermal separation of tissue at the treated tissue whileminimizing or reducing the risk of damage to the retina. These laser andscanning parameters may include, for example, laser wavelength, laserbeam power, spot size at the treated tissue, fluence and peakirradiation at the treated tissue, spot size on the retina, fluence andpeak irradiation on the retina, scanning speed, temporal profile of thelaser beam during the scan, and scanning pattern size and location onthe retina.

Typically, a treatment beam from a continuous wave laser traces thetreatment beam pattern in a single pass in a time period of, forexample, less than about 10 seconds, less than about 5 seconds, lessthan about 1 second, about 10 seconds, about 5 seconds, or about 1second. The treatment beam may move across the treated tissue at aspeed, for example, of about 20 millimeters/second (mm/s) for a 1 secondscan to about 2 mm/s for a 10 second scan, but any suitable scanningspeed and duration may be used. The formation of irregularities or tearsin the resulting rim of tissue is reduced or avoided because movement ofthe continuous wave laser beam along the treatment path occurs duringirradiation of the treated tissue (rather than between discrete laserpulses, for example), and thus all portions of the rim are formed withthe same or similar irradiation and thermal conditions. Using a singlepass of the treatment beam also helps to ensure completion of thecapsulorrhexis even if there is slight movement of the eye relative tothe trajectory.

In variations in which the treatment beam path begins on the interior ofthe closed curve of the treatment pattern (see FIG. 4C, for example),the initial scanning speed in the interior portion of the treatment pathmay be less than the scanning speed along the closed curve. The scanningspeed on the interior portion may, for example, ramp up to the speedused along the closed curve. The average speed along the interiorportion may be, for example, about ½ of the scanning speed used alongthe closed curve, or about ⅔ of the scanning speed used along the closedcurve, or between about ½ and about ⅔ of the scanning speed used alongthe closed curve.

Referring now to the plot of laser power versus time shown in FIG. 16for an example treatment beam scan, at the beginning of a treatment scanthe power in the treatment beam may be ramped up slowly (and optionallymonotonically, as shown, to be efficient with time). As noted above inthe summary section, this slow ramp up may allow the tissue near thestarting point of the pattern to initially stretch without separating,thereby reducing the shear stress/tension at the start of the pattern.This slow ramp up may also avoid or minimize local shock waves in thefluid adjacent to the target tissue that might otherwise be generated bya faster thermal turn-on. For example, the laser beam may ramp-upmonotonically from zero to about 90% of full treatment power over aperiod of from about 5 milliseconds (ms) to about 200 ms, for exampleabout 100 ms. This ramp-up of power typically occurs while the laserbeam is scanned along an initial portion of the treatment path. Invariations in which the treatment beam path begins on the interior ofthe closed curve of the treatment pattern (see again FIG. 4C, forexample), the ramp-up in laser beam power may occur along the initialinterior portion of the treatment path and be complete before the laserbeam reaches the closed curve portion of the treatment pattern. In suchvariations the scanning speed of the beam along the initial interiorportion of the treatment path may also ramp up to the speed used alongthe closed curve, as described above. The average speed along theinterior portion of the path may be about 25% of the scanning speed usedalong the closed curve, for example.

As shown in FIG. 16, turn-off of the treatment laser beam pulse at theend of the treatment scan may be much more abrupt than turn-on.

As noted earlier in this specification, the treatment laser beamwavelength may be selected to be strongly absorbed by a light absorbingagent optionally added onto or into the tissue to be treated. Thetreatment laser may operate at a wavelength of about 577 nanometers, orabout 590 nanometers, or about 810 nanometers, for example. In suchexamples the light absorbing agent, if used, may be Trypan Blue orIndocyanine Green, respectively. Alternatively, the treatment laserwavelength may be selected to be absorbed or strongly absorbed by thetissue itself. Any suitable wavelength for the treatment beam may beused.

As described in more detail below, typically the treatment laser beam isfocused to a waist at or near the location of the tissue to be treated,and then expands in diameter as it propagates to the retina. Also,typically the scanning pattern is expanded on the retina compared to itssize on the treated tissue. Consequently, parameters such as fluence andpeak irradiation for the treatment beam may have different and largervalues at the treated tissue compared to their values at the retina.

The methods and devices disclosed herein typically rely on laser inducedthermal separation of tissue rather than on laser induced ablation, andmay therefore use much lower treatment beam fluence and peak irradiationvalues at the treated tissue than typically required by other laserbased surgical procedures. In addition, the methods and devicesdisclosed herein may use treatment laser beams having relatively highaverage power without producing peak irradiation values that arepotentially damaging to the retina or other eye tissue, because thesemethods and devices may use long (e.g., 1 to 10 second) pulses from acontinuous wave laser. In contrast, laser based surgical proceduresusing much shorter Q-switched or mode-locked laser pulses may berequired to operate at much lower average powers to avoid potentiallydamaging peak irradiance values, which may increase the time required toprovide a desired fluence.

The average power of the treatment beam, which is selected depending inpart on the absorption strength of the absorbing agent at the treatmentbeam wavelength or the absorption strength of the treated tissue at thetreatment beam wavelength, may be for example about 300 mW to about 3000mW. Any suitable average power may be used.

The treatment beam fluence on a particular tissue depends on the averagepower in the treatment beam, the diameter of the treatment beam at thattissue, and the scanning speed of the treatment beam across that tissue.For the methods and devices disclosed herein, at the tissue to betreated (e.g., the anterior lens capsule) the treatment beam fluence fora 1 second scan may be for example about 80 Joules/centimeter² (J/cm²)to about 450 J/cm². For a 5 second scan the fluence at the tissue to betreated may be for example about 100 J/cm² to about 1600 J/cm². For a 10second scan the fluence at the tissue to be treated may be for exampleabout 100 J/cm² to about 2000 J/cm².

The treatment beam peak irradiance on particular tissue depends on thepeak power in the treatment beam and the diameter of the treatment beamat that tissue. For the methods and devices disclosed herein, at thetissue to be treated (e.g., the anterior lens capsule) the treatmentbeam peak irradiance may be, for example, less than about 2,000Watt/centimeter² (W/cm²), or less than about 5,000 Watt/centimeter²(W/cm²), or less than about 10,000 W/cm², or less than about 100,000W/cm², or less than about 200,000 W/cm². For example, in some variationsthe peak irradiance on the anterior lens capsule is about 2,100 W/cm²and the fluence at the anterior lens capsule is about 130 J/cm².

In general, at the retina the treatment beam fluence may be, forexample, less than about 10 J/cm² and the irradiance may be, forexample, less than about 400 milliwatts/cm² (mW/cm²). In one embodimentwith an NA of about 0.06 and a beam diameter of about 2000 microns onthe retina, for a 1 second scan speed, the fluence at the retina may forexample have a maximum of about 0.3 J/cm². For a 5 second scan thefluence at the retina may for example have a maximum of about 1.5 J/cm².For a 10 second scan the fluence at the retina may for example have amaximum of about 3.0 J/cm².

Referring now to FIG. 17, the inventor has discovered that the minimumtreatment laser beam power required for laser induced separation oftissue has a non-linear response to the irradiated beam area on thetreated tissue. In particular, this plot demonstrates that there is alow dependence of the power required for tissue separation on the sizeof the irradiated area, specifically below a beam diameter of about 100to about 200 microns. However, as the spot size increases far above adiameter of about 300 microns, more power is required to separatetissue.

Hence it may be preferable to use a treatment beam having a diameter ofabout 200 microns at the treated tissue. This may reduce the requiredirradiance in the treatment beam and thus decrease the risk of damagingthe retina. More generally, the treatment laser beam may have a diameterof, for example, about 50 microns to about 400 microns at the treatedtissue.

Use of Surgical Contact Lens

A surgical contact lens may be used to neutralize or approximatelyneutralize the cornea's focusing power on the retina to further reducerisk of damaging the retina, and in particular to protect the fovea.(The fovea is located in the center of the macula region of the retina,and is responsible for sharp central vision). FIG. 18A demonstrates thatin the absence of a surgical contact lens, a scanned treatment laserbeam pattern 1800 centered around the visual axis 1810 would be focusedinto the proximity of the fovea 1820 on the retina. It is likely thatthe fovea would be under constant irradiation for the full duration ofthe scanned pattern. FIG. 18B demonstrates that in the presence of asurgical contact lens 1830 with a mild convex anterior surface 1840minimizing the majority of the corneal optical lens power, a scannedlaser beam pattern 1800 centered around the visual axis 1810 may beprojected onto the retina such that it avoids the fovea and insteadsurrounds the fovea. FIG. 18C demonstrates that in the presence of asurgical contact lens 1830 with a concave anterior surface 1850, ascanned laser beam pattern 1800 centered around the visual axis may beprojected on to the retina so that it avoids the fovea and insteadsurrounds the fovea. Moreover, the trace of the laser beam projected onto the retina may be further refracted way from the fovea than would bethe case for a convex surgical contact lens. In addition the areairradiated by the laser beam would be larger on the retina, whichreduces the delivered laser energy per unit area (fluence) on theretina.

Use of a surgical contact lens as just described to refract the scannedtreatment beam pattern away from the fovea allows the treatment laser tobe operated at a higher power, without damaging the fovea or otherportions of the retina, than might otherwise be the case. Such use of asurgical contact lens is optional, however.

Treatment/Scanning Device

Referring now to FIG. 19, an example device 1900 may be used to performophthalmic surgeries as described herein. FIG. 19 illustrates theoptical beam focusing and the scanner optical properties of this device.Device 1900 comprises an optical fiber 1910 that delivers collinearvisualization and treatment laser beams 1920 (e.g. from treatment laser1922 and visualization laser 1924) to a lens 1930, which focuses thebeams beyond a two-dimensional scanner 1940. The two-dimensional scanner1940 scans the visualization or treatment laser beam to provide thedesired visualization or treatment beam pattern. Lens 1950 focuses thetreatment and visualization laser beams to a waist in the treated eye1960 at or approximately at the anterior lens capsule 1970. Afterpassing through that waist the laser beams expand and are thus defocusedon the retina. Optional stationary final mirror 1980 may be used asshown to direct the beams to be collinear or nearly collinear withmicroscope optics (see FIGS. 20, 21, and 25).

The two-dimensional scanner 1940 has different tilt positions to createa scanned pattern on the anterior capsule. The solid line depiction ofthe scanner represents one example tilt position, and the dash linedepiction of the scanner represents a second tilt position. In thisexample device the optics are designed such that there is a scannerpattern invariant 1985 (a location at which there is no apparent motionof the scanned pattern) and waist between the lens 1950 and its focus.Compared to a system lacking a scanner pattern invariant located in thismanner, this arrangement has the advantages of reducing or minimizingthe size of the optical device, reducing or minimizing the requiredtwo-dimensional scanner tilt, reducing or minimizing the area requiredon the optional final mirror, and providing additional divergence of thescanned pattern along the optical path so that for the same size andshape pattern on the anterior capsule, the projection on the retina hasa larger diameter and therefore less fluence and less associatedtemperature rise at the retina.

Example device 1900 also includes an optional light detector 1990. Thetwo-dimensional scanner 1940 may deflect the treatment or visualizationlaser beams to detector 1990, which may be used for example to measuretheir power. Detector 1990 may be a detector array, for example, inwhich case the two-dimensional scanner 1940 may scan the treatment orvisualization laser beam across the detector array to confirm that thescanner is functioning properly.

Device 1900 further includes an optional aberrometer 1995, which may beused to make refractive measurements of the eye to be treated. This maybe accomplished, for example, by tilting the two-dimensional scanner1940 to direct an output light beam from aberrometer 1995 along theoptical path used for the visualization and treatment beams into theeye. Alternatively, a light beam from aberrometer 1995 could optionallybe introduced into the optical path of device 1900 with a dichroic beamsplitter, for example.

Device 1900 includes a scanner controller 1928. The scanner controllermay be preprogrammed with one or more treatment beam pattern shapes andone or more visualization pattern shapes by the manufacturer, forexample. At or prior to the time of treatment an operator may then, forexample, select treatment and visualization pattern sizes and shapes tobe used in a particular treatment procedure.

Any other suitable device design may also be used to perform theprocedures described herein.

Integration with Microscope

Example device 1900 described above may be integrated with a microscope.FIG. 20 shows an example in which device 1900 is externally integratedwith a microscope 2000. The integration is external because device 1900and microscope 2000 do not share any optical elements. Microscope 2000may be used by a human operator 2010 (eye only shown) to observe the eye1960 to be treated and the visualization pattern prior to, during, andafter the treatment procedure.

FIG. 21 shows an example in which device 1900 of FIG. 19 is internallyintegrated with a microscope to provide an integrated device 2100. Inthis integrated device, the treatment and visualization beam paths passthrough the microscope objective 2110, and illumination for themicroscope is provided by light output from an optical fiber 2120 alonga path that shares stationary mirror 1980 with the treatment andvisualization beam paths.

Any other suitable integration with a microscope may also be used.

Depth Alignment

A preliminary step in using device 1900 is to adjust the position of thedevice, or of the optical elements within the device, with respect tothe patient's eye so that the waist (focus) of the treatment beam is ator approximately at the tissue to be treated. This may be done, forexample, by viewing a visualization pattern (e.g., as described above)that is projected onto the tissue to be treated and adjusting device1900 to bring the visualization pattern into focus on the tissue.However, in this approach any uncorrected deficiency in the operator'svision (e.g., myopia) may affect the operator's judgment as to whetheror not the visualization pattern is in focus on the tissue to betreated. This may result in an incorrect adjustment of the treatmentdevice.

Referring now to FIG. 22, an example device 2200 for performingophthalmic surgeries includes, in addition to the elements of device1900 shown in FIG. 19, optical elements that produce a secondvisualization beam to facilitate depth alignment of the device. Inparticular, in a depth alignment mode, further described below, scanner1940 in device 2200 dithers to direct a visible light visualization beam1920 from optical fiber 1910 along two different optical paths toproduce visualization beams 2210 and 2215. Scanner 1940 may ditherbetween the two paths at a rate greater than or equal to about 30 Hertz,for example, so that flickering of the two beams is not typicallynoticeable to an operator.

Beam 2210 follows the optical path of the treatment and visualizationlaser beams described above with respect to FIG. 19, and may be scannedto produce any suitable pattern. Beam 2215 may also be scanned toproduce any suitable pattern. Beam 2215 is directed to intersect beam2210 at or approximately at the treatment beam waist. As furtherdescribed below, the intersection of beams 2210 and 2215 may thereforebe used to identify the location of the treatment beam waist and todetermine whether or not the treatment beam waist is properly positionedat the tissue to be treated. In the illustrated example, beam 2215 isdirected to intersect beam 2210 using mirror 2220 and lens 2230 but anyother suitable optical arrangement producing the desired intersectionmay also be used. Lens 2230 typically focuses beam 2215 to a tight waistat the intersection of the two beams, to identify the location of thatintersection with greater precision.

If the intersection of beams 2210 and 2215 (and thus the treatment beamwaist) is not properly positioned at the treatment tissue, the positionof device 2200 or of optical elements within the device may be adjustedwith respect to the patient's eye to move the intersection of thevisualization beams, and thus the treatment beam waist, to the desiredposition.

Referring now to FIGS. 23A-23C, in some variations beam 2210 is scannedto produce a line 2310 and beam 2215 is not scanned but instead focusedto a tight waist that appears as a dot 2315 in these figures. Device2200 is aligned (e.g., by the manufacturer) so that beams 2210 and 2215intersect at or approximately at the location of the waist of thetreatment beam, with the dot 2315 centered or approximately centered online 2310. FIGS. 23A-23C show a view through a microscope (e.g.,microscope 2000 of FIG. 20) of the tissue to be treated (e.g., the lenscapsule). When the intersection of visualization beams 2210 and 2215 isnot positioned at or approximately at the tissue to be treated, dot 2315and line 2310 will appear to be displaced from each other as shown inFIGS. 23A-23B. Further, an operator may be able to determine whether thevisualization beams intersect in front of or behind the tissue to betreated based on which side of line 2310 the dot 2315 appears to belocated. After device 2200 is adjusted to position the intersection ofbeams 2210 and 2215 (and therefore the waist of the treatment beam) ator approximately at the tissue to be treated, line 2310 and dot 2315will appear superimposed as shown in FIG. 23C.

Although the illustrated example uses a line 2310 and a dot 2315, anyother suitable patterns for intersecting beams 2210 and 2215 may be usedto identify and adjust the position of the treatment beam waist withrespect to the tissue to be treated. Typically the visualizationpatterns used in depth alignment mode differ from those describedearlier in this specification. Although in the illustrated exampleintersecting beams 2210 and 2215 are produced from a singlevisualization laser beam by dithering the scanner 1940, any othersuitable method of intersecting visible beams to identify the locationof the treatment beam waist may also be used. Beams 2210 and 2215 mayhave the same wavelength, as in the example just described, or differentwavelengths.

Device 2200 may be switchable between several different operating modesincluding the depth alignment mode just described. For example, in somevariations device 2200 may be switchable between at least the followingmodes:

-   -   Standby Mode: The treatment beam and all visualization beams are        off.    -   Depth Alignment Mode: As described above, intersecting        visualization beams are used to facilitate adjusting the        position of the focus of the treatment beam optical system with        respect to the position of the tissue to be treated. The        treatment beam is not activated.    -   Ready Mode: Visualization patterns are projected onto the lens        capsule to guide the treatment. The visualization patterns may        facilitate alignment of the treatment beam with respect to        anatomy of the eye, and/or indicate the desired perimeter of a        rhexis to be produced with the treatment beam.    -   Fire Mode: Treatment laser beam emission is activated and        incident on the tissue to be treated.

Referring to FIG. 24A, some variations of device 2200 may include afoot-operable control 2400 in which a first button 2405, located on topof shroud 2410 for example, may be activated to switch from Standby toDepth Alignment Mode, with the device remaining in Depth Alignment Mode.Button 2405 may be activated again to switch from Depth Alignment Modeto Ready Mode, with the device remaining in Ready Mode. While the deviceis in Ready Mode, a shrouded fire button 2415 may be activated to switchfrom Ready Mode to Fire Mode, activating the treatment beam and thetreatment beam scan, after which the device returns to Standby Mode.Alternatively, button 2405 may be activated again to switch from ReadyMode to Standby Mode.

Some variations of device 2220 may also be switchable into and out of aVisualization Sizing Mode. In the Visualization Sizing Mode, avisualization sizing pattern is projected onto the anterior lens capsuleto guide positioning of the desired rhexis and thus positioning of thedesired closed curve of the treatment beam. The size (e.g., diameter oranother dimension) of the visualization sizing pattern is adjustable toincrease or decrease a corresponding dimension of the desired rhexis tobe formed by the treatment beam. In these variations, the device may beswitched between modes in the following order, for example: StandbyMode, Depth Alignment Mode, Visualization Sizing Mode, Ready Mode,Standby Mode. This may be done, for example, by sequential activation ofbutton 2405 (FIG. 24A) as described above. The visualization sizingpattern projected during Visualization Sizing Mode may have the samegeometry as the visualization pattern projected in Ready Mode, or bedifferent. It may be advantageous for the visualization sizing patternto differ in geometry from the visualization pattern, to make it easierfor an operator to recognize in which mode the device is in.

Referring to FIG. 24B, foot operable control 2400 may further includebuttons 2420A and 2420B, located on interior or exterior side walls ofthe shroud for example, that may be used to increase or decrease thesize of the visualization pattern projected during Visualization SizingMode (and correspondingly increase or decrease the desired radius oranother dimension of the rhexis to be formed by the treatment beam).

Any other suitable switching mechanism may be used to switch between theoperating modes just described. The switching mechanism may be orinclude switches intended to be hand operated, for example. Further,variations of foot-operable control 2400 described above, or of anyother suitable switching mechanism, may be configured to allow thedevice to be switched from Depth Alignment Mode to Standby Mode, fromVisualization Sizing Mode (if available) to Depth Alignment Mode, orfrom Ready Mode to Visualization Sizing Mode (if available) or DepthAlignment Mode. This may be accomplished using additional switchingbuttons for these transitions, for example, or with a button thatreverses the direction in which button 2405 moves the device through thesequence of modes.

Virtual Visualization Patterns

As described above, visualization patterns may be projected onto theanterior lens capsule with one or more scanned visualization laser beamsto aid in the ophthalmic surgical procedure. As an alternative to suchprojected visualization patterns, virtual visualization patterns may bepresented on a display and overlaid with a view of the anterior lenscapsule to aid in the surgical procedure. These patterns are virtual inthat they are presented as simulated images on the display but notactually projected onto the anterior lens capsule. Any of thevisualization patterns described above, and any other suitablevisualization patterns, may be presented as virtual visualizationpatterns in this manner. Such virtual visualization patterns may be usedfor any of the purposes described above with respect to projectedvisualization patterns. The Ready Mode of operation and the optionalVisualization Sizing Mode of operation described above may employvirtual visualization patterns rather than projected visualizationpatterns, for example. Consequently, variations of the treatment devicesdescribed herein may employ treatment laser beams but lack the collinearvisualization laser beam described with respect to FIG. 19, for example.

For example, FIG. 25 shows a laser scanning treatment device 2500similar to that of FIG. 19 externally integrated with a microscope 2510.Microscope 2510 includes a heads-up display 2520 on which a virtualvisualization pattern may be overlaid with a view through the microscopeof the surgical field to which a treatment beam 1920 is directed. Device2500 may optionally provide a visualization beam collinearly withtreatment beam 1920 to also provide a projected visualization pattern,but that is not necessary. Device 2500 may be internally integrated witha microscope employing a heads-up display to present virtualvisualization patterns overlaid with the surgical field, rather thanexternally integrated as shown in FIG. 25. Such internal integration maybe done similarly to as shown in FIG. 22, for example. In addition todisplaying one or more virtual visualization patterns overlaid with thesurgical field, heads-up display 2520 may display data or parametersrelating to the surgical procedure. For example, the display may reportthe size or diameter of the rhexis to which the displayed virtualvisualization pattern corresponds and/or the current mode of operationof the treatment device (e.g., Standby, Depth Alignment, VisualizationSizing, Ready, Fire, as described above).

Determining the Visual Axis

Typically, it is desirable to center the rhexis on the visual axis ofthe eye. Referring for example to FIGS. 19-22 and 25, the visual axismay be determined during an ophthalmic surgical procedure by directing alow power visible laser beam 1920 to the eye and having the patientfixate on the beam (look directly into it). When the patient is fixatedon the laser beam, the laser beam is collinear with the visual axis ofthe patient's eye. Laser beam 1920 may be the treatment beam at lowpower, for example, a visualization laser beam, or another low powervisible laser beam. The laser beam may be made to blink at a frequencyperceptible by the patient, for example at less than about 30. Hertz, tomay make it easier for the patient to fixate on it. The blinking ratemay be varied, randomly for example, to further facilitate the patientfixating on the beam.

Such a blinking laser beam 1920 may be directed to the eye along orapproximately along the optical axis of a microscope used in theophthalmic surgical procedure (e.g., as in FIGS. 20-22 and 25) so thatthe location of the visual axis in the surgical field may be viewedthrough the microscope by an operator and/or with a camera (not shown).The offset of the visual axis from the center of the limbus or dilatedpupil may thereby be measured, if desired. If virtual visualizationpatterns are being used on a heads-up display, as described above, theyand the corresponding treatment beam path may be adjusted to center therhexis on the visual axis or otherwise adjust the location and/ororientation of the rhexis with respect to the visual axis. Ifvisualization patterns are instead being projected onto the anteriorlens capsule with a scanning visualization beam, they and thecorresponding treatment beam path may by similarly adjusted with respectto the visual axis.

Orientation of a Toric IOL

A toric IOL has a different optical power and focal length along twoperpendicular axes. Toric IOLs are typically implanted with a preferredorientation that compensates for astigmatism or other opticalaberrations in the eye. Proper orientation of a toric IOL may bedetermined using a (optionally blinking) laser beam on which the patientis fixated, as described above, by viewing a reflection of the laserbeam from the back of the eye (e.g., the retina) after it has passedback through the toric IOL. The reflection may be viewed through amicroscope (as in FIGS. 20-22 and 25, for example), either directly byan observer or with a camera (not shown). If the toric IOL orientationis not correct, the reflection from the back of the eye as viewedthrough the toric will be weak and have an elliptical shape. If thetoric IOL orientation is correct, the reflection from the back of theeye will be stronger and will appear as a smaller and rounder spot.

The view of the reflection of the laser beam from the back of the eyemay be enhanced by using a linearly polarized laser beam and viewing thereflection from the back of the eye through a crossed polarizer.Reflections of the laser beam from front surfaces of the eye (e.g., thecornea) and from the IOL will tend to retain the linear polarization ofthe incident laser beam. The reflection from the back of the eye, whichmay be better described as scattered rather than reflected light, willbe less polarized than the incident laser beam. The crossed polarizerwill therefore tend to reject a substantial portion of the reflectionsfrom the front surfaces of the eye and from the IOL, but pass asubstantial portion of the light reflected or scattered from the back ofthe eye.

Eye Tracking

The position of the pupil or other features of the eye may be trackedwith the devices and methods described above by imaging the eye underinfrared illumination with a camera. Changes in the eye position duringthe ophthalmic surgery (before or during use of the treatment laserbeam) may be fed back to a control system for the scanning lasertreatment device to adjust the aim of the treatment laser accordingly.

Detecting A Light Absorbing Agent

In variations of the procedures described herein in which a lightabsorbing agent is used to facilitate laser assisted thermal tissueseparation to create an opening in an anterior lens capsule, it may bedesirable to optically or visually confirm that the light absorbingagent has been correctly placed prior to performing the treatment. Inparticular, it may be desirable to confirm that sufficient lightabsorbing agent is present on or in the capsule to prevent transmissionof the treatment beam through the capsule at levels that might damagethe retina or other portions of the eye interior. It may also bedesirable to confirm that sufficient light absorbing agent is present onor in the capsule to result in complete thermal separation of thecapsule along the treatment beam path.

Unsafe transmission of the treatment beam through the capsule mightpotentially occur if the treatment beam intensity incident on thetreated tissue is above a predetermined threshold deemed safe for theretina and, for the speed (dwell time) at which the treatment beam isscanned on the treated tissue, there is insufficient light absorbingagent present in the treated tissue to absorb sufficient treatment beamlight to reduce the treatment beam intensity transmitted through thetreated tissue to below the safety threshold. Unsafe transmission of thetreatment beam through the capsule might also potentially occur if thetreatment beam intensity incident on the treated tissue is above thepredetermined threshold deemed safe for the retina and the treatmentbeam intensity and scanning speed result in thermal tissue separationoccurring or reaching completion at a location on which the treatmentbeam is still incident. Preferably, thermal tissue separation occurs orreaches completion at a particular location on the treatment beam pathafter the treatment beam has scanned past that location.

Unsafe transmission of the treatment beam through the capsule may beprevented, for example, by placing a sufficient amount of lightabsorbing agent on the tissue to be treated, selecting the treatmentbeam scanning speed to be sufficiently fast, and/or selecting thetreatment beam intensity (determined by power and spot size) incident onthe treated tissue to be sufficiently low.

For example, FIG. 26A shows an oscilloscope trace for a measurement inwhich a laser beam having a wavelength of about 577 nanometers and apower suitable for a treatment beam is focused to a stationary spothaving a diameter of about 200 microns on an anterior lens capsule (froma cadaver) for about 450 milliseconds. The anterior lens capsule hasbeen treated with the light absorbing agent Trypan Blue. The horizontalaxis of the oscilloscope trace represents time and the vertical axisrepresents transmission of the treatment beam through the capsule, withtransmission increasing in the downward direction along the verticalaxis. For clarity, the data of FIG. 26A are also presented in thetransmission versus time plot of FIG. 26B with transmission increasingin the upward direction along the vertical axis.

As these figures show, under the conditions of this measurement thetransmission of the treatment beam through the lens capsule initiallyslowly increases with time and then levels out at about 20%, followed bya sudden transition (breakthrough) to a much higher transmission thatoccurs at about 80 milliseconds. A scanning treatment beam with the samewavelength, power, and spot size might have a dwell time at any givenlocation on the treatment beam path of less than or equal to about 60milliseconds, for example, in which case “breakthrough” would not occurduring scanning.

The quantity of the light absorbing agent present on or in the lenscapsule may be assessed, for example, by measuring the reflection ofbroad band (e.g., white) light from the lens capsule and (optionally)the iris, the scleral regions, and/or a surgical contact lens. The broadband light may be provided, for example, using conventional microscopeillumination in combination with a microscope integrated with thetreatment devices described above, and the intensity of the reflectionof the broad band light may be measured, for example, with aconventional still or video camera integrated with the microscope.Images of the reflected light may be analyzed, for example, with aconventional computer. Additionally, or alternatively, the lightabsorbing agent may be assessed by similarly measuring the intensity ofthe reflection of a narrow band detection laser beam from the lenscapsule and (optionally) the iris, the scleral regions, and/or asurgical contact lens. In treatment devices described above, thedetection laser beam (e.g. from detection laser 1926 in FIG. 19) may beprovided through the same optical fiber that delivers the treatment andvisualization beams, for example. The visualization pattern laser mayprovide the detection laser beam, for example. A detection laser may,for example, be scanned along the treatment path to determine thepresence and quantity of light absorbing agent on the treatment path.

Depending on the wavelength at which the reflectance measurement ismade, the light absorbing agent when present in or on the capsule mayaffect reflection from the capsule either by absorbing light and thusdecreasing reflection from the capsule, or by reflecting light morestrongly than the capsule tissue and thus increasing reflection from thecapsule. (The light absorbing agent is more strongly absorbing than thecapsule tissue at the treatment wavelength, but may be more reflectivethan the capsule tissue at other wavelengths). In either case,reflection measurements may be used to assess the amount of lightabsorbing agent present on or in the capsule.

The reflection measurements may be made both before and afterintroduction of the light absorbing agent to the lens capsule. Asfurther discussed below, this may allow determination of abackground-corrected relative reflectance resulting from the lightabsorbing agent, for example by determining the difference between theintensities of the reflections from the capsule measured before andafter the light absorbing agent has been applied to the capsule.Typically, the light absorbing agent is not applied to the iris, thescleral regions, and any surgical contact lens used and thus should notaffect reflection from the iris, the scleral regions, and the surgicalcontact lens. Consequently, as further discussed below, the reflectionsfrom the iris, the scleral regions, and the surgical contact lensmeasured before and after application of the light absorbing agent tothe capsule may be used to adjust (e.g., normalize, scale, or backgroundcorrect) the reflection intensities from the capsule. These adjustmentsmay compensate, for example, for small changes in orientation of the eyeoccurring between the “before” and “after” measurements or for otherdifferences in the reflection measurements unrelated to application ofthe light absorbing agent. The “before” and “after” measurements of theintensities of the reflections from the iris, the scleral regions, andthe surgical contact lens may also allow the absolute reflectanceresulting from the light absorbing agent on or in the capsule to bedetermined.

FIG. 27A shows example images and FIG. 27B shows a plot of relativereflectance that illustrate a decrease in the relative reflectance ofbroad band illumination from a lens capsule as the amount of lightabsorbing agent applied to the capsule is increased. Similarly, FIG. 28Ashows example images and FIG. 28B shows a plot of relative reflectancethat illustrate a decrease in the relative reflectance of narrow band(red) visualization laser illumination from a lens capsule as the amountof light absorbing agent applied to the capsule is increased.

In some variations, a computer implemented automatic anatomicalrecognition algorithm identifies the capsule region and optionally theiris and/or scleral regions of images of broad band light reflected fromthe eye before the light absorbing agent is applied to the capsule. Red,green, and/or blue reflection intensity values, optionally spatiallyaveraged, are determined in the capsule region and optionally in theiris and/or the scleral regions of the images. Bright regions of theimages in which the light detector (e.g., camera) may have saturated areprocessed independently and may or may not be used. The automaticrecognition algorithm may adjust the illumination level to ensureaccurate capsule identification and reflectance measurements, andoptionally to reduce saturated regions. Similarly, the computerimplemented automatic anatomical recognition algorithm identifies thecapsule region and optionally the iris and/or scleral regions of imagesof broad band light reflected from the eye after the light absorbingagent is applied to the capsule. Red, green, and/or blue reflectionintensity values, optionally spatially averaged, are determined in thecapsule region and optionally in the iris and/or sclera regions of theimages. Bright regions of the images in which the light detector (e.g.,camera) may have saturated are processed independently and may or maynot be used. The automatic recognition algorithm may adjust theillumination level to ensure accurate capsule identification andreflectance measurements, and optionally to reduce saturated regions.

Relative reflectance of red, green, and/or blue of the capsule relativeto the iris may be calculated from the measured intensities for both the“before” and “after” images. Alternatively, or in addition, relativereflectance of red, green, and/or blue of the capsule relative to thescleral regions may be calculated from the measured intensities for boththe “before” and “after” images. Alternatively, or in addition, relativereflectance of red, green, and/or blue of the capsule relative to theaverage total intensity for the image may be calculated from themeasured intensities for both the “before” and “after” images.Alternatively, or in addition, relative reflectance of red, green, andor blue of the capsule for a fixed illumination intensity may becalculated from the measured intensities for both the “before” and“after” images. These variously determined reflectance values may beused to assess the quantity of light absorbing agent present in or onthe capsule.

In other variations, a computer implemented automatic anatomicalrecognition algorithm identifies the capsule region and optionally theiris and/or scleral regions of images of narrow band (e.g., detectionlaser) light reflected from the eye before the light absorbing agent isapplied to the capsule. Reflection intensity values, optionallyspatially averaged, are determined in the capsule region and optionallyin the iris and/or the scleral regions of the images. Bright regions ofthe images in which the light detector (e.g., camera) may have saturatedare processed independently and may or may not be used. The automaticrecognition algorithm may adjust the illumination level to ensureaccurate capsule identification and reflectance measurements, andoptionally to reduce saturated regions. Similarly, the computerimplemented automatic anatomical recognition algorithm identifies thecapsule region and optionally the iris and/or scleral regions of narrowband (e.g., detection laser) light reflected from the eye after thelight absorbing agent is applied to the capsule. Reflection intensityvalues, optionally spatially averaged, are determined in the capsuleregion and optionally in the iris and/or scleral regions of the images.Bright regions of the images in which the light detector (e.g., camera)may have saturated are processed independently and may or may not beused. The automatic recognition algorithm may adjust the illuminationlevel to ensure accurate capsule identification and reflectancemeasurements, and optionally to reduce saturated regions.

Relative reflectance of the capsule relative to the iris may becalculated from the measured intensities for both the “before” and“after” images. Alternatively, or in addition, relative reflectance ofthe capsule relative to the scleral regions may be calculated from themeasured intensities for both the “before” and “after” images.Alternatively, or in addition, relative reflectance of the capsulerelative to the average total intensity for the image may be calculatedfrom the measured intensities for both the “before” and “after” images.Alternatively, or in addition, relative reflectance for a fixedillumination intensity may be calculated from the measured intensitiesfor both the “before” and “after” images. These variously determinedreflectance values may be used to assess the quantity of light absorbingagent present in or on the capsule.

In the reflectance measurement and analysis methods just described,automated anatomical recognition of a microscope view of the iris,capsule and sclera may be implemented by analyzing the image todetermine three major regions. A primary region that is approximatelycircular represents the capsule or pupil, and typically has a diameterof about 4 mm to about 12 mm. A second region is an approximatelycircular band concentric to the primary region, and typically has awidth of about 0.5 mm to about 5 mm. This second region represents theiris. The color texture from the image for this region may be from thereflection of the structured pigmented tissue, and may be utilized inthe automated recognition. A third region is concentric to the primaryand secondary regions, and represents the sclera. This regioneffectively reflects the illumination light and may have structuredblood vessels that may be utilized in the automated recognition.

If the light absorbing agent absorbs light at the wavelengths at whichrelative reflectance is measured, then the relative reflectancemeasurements will be positively correlated with transmission of thetreatment beam through the capsule. That is, as the amount of lightabsorbing agent in the capsule is increased, both the relativereflectance (of a detection laser or of a component of broad bandillumination, for example) and the transmission of the treatment beamwill decrease. An example of this situation is shown in the plots ofFIG. 29 and FIG. 30, for example.

Such a correlation between relative reflectance and treatment beamtransmission may be measured on eyes from cadavers, for example, andthen used to inform or control treatment on live patients.

For example, safe treatment may require that transmission of thetreatment beam through the capsule be less than some predeterminedthreshold value, which correlates with a particular threshold relativereflectance value. In FIG. 30, for example, a 20% transmission thresholdvalue corresponds to a 60% relative reflectance threshold value. Ifrelative reflectance measured on the patient's eye after the lightabsorbing agent has been administered is less than the thresholdreflectance value, then transmission of the treatment beam through thecapsule is below the allowed limit and treatment may proceed. Ifrelative reflectance is too high, then for example additional lightabsorbing agent may be administered until the relative reflectance ismeasured to be at or below the threshold relative reflectance value.

Alternatively or in addition, after the light absorbing agent has beenadministered, treatment parameters such as, for example, treatment laserpower, wavelength, spot size, and/or scanning speed may be selectedand/or controlled based on the relative reflectance measurements so thatthe treatment is optimally performed and the transmission of thetreatment beam through the capsule remains below a predeterminedthreshold value throughout the treatment. The treatment device may forexample utilize a look-up table mapping treatment parameters ontoreflectance measurements.

The reflectance measurements may also be used, for example, to confirmthat sufficient light absorbing agent is present along the treatmentbeam path to result in complete laser thermal separation of the anteriorcapsule, when the selected/preprogrammed treatment beam parameters areapplied. This may be achieved for example by analyzing (as describedabove for example) images in the region that includes the completetreatment path, to ensure that the reflectance is below a predetermined(e.g., preprogrammed) value along the entire path.

In an alternative approach, the light absorbing agent may be detected byexciting and detecting fluorescence from the light absorbing agent. Thismay done, for example, using the treatment beam or an attenuated portionof the treatment beam. Such a measurement may optionally be made awayfrom the treatment location to avoid depleting light absorbing agentrequired for the treatment scan. Fluorescence indicating the presence ofthe light absorbing agent may be observed or detected, for example,through a microscope integrated with the treatment device as describedabove.

This disclosure is illustrative and not limiting. Further modificationswill be apparent to one skilled in the art in light of this disclosureand are intended to fall within the scope of the appended claims. Forexample, in some variations pulsed lasers may be used instead ofcontinuous wave lasers to produce visualization and/or treatment laserbeams in the methods and devices described above. Also, although thetreatment beam is described above as causing thermal tissue separationalong the closed curve without ablating anterior lens capsule tissue,devices and methods described herein may instead employ a treatment beamthat causes separation of tissue along the closed curve by otherlaser-induced mechanisms such as laser-induced ablation of tissue, forexample. In particular, the various treatment beam patterns, projectedand virtual visualization patterns, methods for determining the visualaxis of the eye, methods for assessing the orientation of a toric IOL,and related methods and devices described herein may be used withtreatment lasers that cause separation of the anterior lens tissue alongthe closed path by any suitable mechanism.

What is claimed is:
 1. A device for creating an opening in the anteriorlens capsule of the eye, the device comprising: a treatment laseroutputting a treatment laser beam; a two dimensional scanner on whichthe treatment laser beam is incident; a scanner controller controllingthe two-dimensional scanner, the scanner controller having one or moreprogrammed scan profiles for predetermined treatment patterns in whichthe treatment laser beam is scanned to form a closed curve at theanterior lens capsule; and a display programmed to display one or morevirtual visualization patterns overlaid with a view of a surgical fieldof the anterior lens capsule to which the treatment laser beam isdirected, each programmed scan profile for the treatment laser beamhaving a corresponding programmed virtual visualization pattern; whereinthe treatment laser beam has a wavelength absorbed by Trypan Blue orIndocynanine Green, a spot size at the anterior lens capsule of greaterthan or equal to 50 microns and less than or equal to 300 microns, and apower of 300 milliwatts to 3000 milliwatts, and absorption of 35% ormore of the treatment laser beam power at the anterior lens capsulecauses thermal denaturing of collagen in the anterior lens capsuleresulting in thermal tissue separation along the closed curve to formthe opening without ablating anterior lens capsule tissue; and whereinfor each programmed scan profile for the treatment laser beam at least aportion of the corresponding virtual visualization pattern representsthe size and location of a perimeter boundary of the opening to becreated in the anterior lens capsule by the treatment laser beam andmatches at least a portion of the perimeter boundary, the perimeterboundary of the opening differing in size and location from the closedcurve of the corresponding predetermined treatment pattern and having alarger diameter than the closed curve of the corresponding predeterminedtreatment pattern.
 2. The device of claim 1, wherein at least a portionof the virtual visualization pattern matches the pupil or limbus of theeye and thereby facilitates aligning the predetermined treatment patternwith respect to those anatomical features.
 3. The device of claim 1,wherein the treatment laser is a continuous wave laser, the treatmentlaser beam is scanned along the closed curve of the predeterminedtreatment pattern in a single pass, and the power of the treatment laserbeam is constant along the closed curve.
 4. The device of claim 1,wherein scanning the treatment laser beam is completed in less than orequal to 10 seconds.
 5. The device of claim 4, wherein scanning thetreatment laser beam is completed in less than or equal to 5 seconds. 6.The device of claim 5, wherein scanning the treatment laser is completedin less than or equal to 1 second.
 7. The device of claim 1, wherein thetreatment beam is focused to a waist at the anterior lens capsule anddiverges as it is incident on the retina of the eye, and thepredetermined treatment pattern diverges in the eye and is consequentlyexpanded in size and area on the retina compared to its size and area atthe anterior lens capsule.
 8. The device of claim 7, wherein thetreatment laser beam provides a fluence of less than or equal to 2000J/cm² along the closed curve of the predetermined treatment pattern atthe anterior lens capsule and a fluence of less than or equal to 10J/cm² along a corresponding closed curve on the retina of the eye. 9.The device of claim 7, wherein the treatment laser beam provides a peakirradiance of less than or equal to 10,000 W/cm² along the closed curveof the predetermined treatment pattern at the anterior lens capsule anda peak irradiance of less than or equal to 400 mW/cm² along acorresponding closed curve on the retina of the eye.
 10. The device ofclaim 7, wherein the treatment laser beam has a diameter of greater thanor equal to 100 microns and less than 300 microns at the anterior lenscapsule.
 11. The device of claim 7, wherein the treatment pattern on theretina avoids the fovea of the eye.
 12. The device of claim 1, whereinat the beginning of the predetermined treatment pattern the power of thetreatment laser beam ramps up from zero to 90% of its full power duringa period of 5 milliseconds to 200 milliseconds.
 13. The device of claim12, wherein the treatment laser beam is scanned from an initial pointinside the closed curve toward the closed curve at a speed less than anaverage speed at which the treatment laser beam is subsequently scannedalong the closed curve, and the ramp-up of treatment laser beam power iscomplete before the treatment laser beam reaches the closed curve. 14.The device of claim 1, comprising a detection laser outputting adetection laser beam having a wavelength that is reflected by TrypanBlue or Indocyanine Green.
 15. The device of claim 1, comprising adetection laser outputting a detection laser beam having a wavelengththat excites fluorescence from Trypan Blue or Indocyanine Green.
 16. Thedevice of claim 1, comprising a broad band light source outputting broadband illumination reflected by Trypan Blue or Indocyanine Green.
 17. Thedevice of claim 16, wherein the broad band illumination is white light.18. The device of claim 1, arranged in combination with a surgicalcontact lens positioned on the eye to neutralize the focusing power ofthe cornea of the eye on the retina of the eye and refract the scanningpattern away from the fovea of the eye.
 19. The device of claim 1,comprising a laser outputting a visible light laser beam blinking at afrequency perceptible to a human patient, directed into the eye, andestablishing the visual axis of the eye upon fixation by the patient onthe visible light laser beam.
 20. The device of claim 19, wherein thepredetermined treatment pattern is centered on the visual axisdetermined by the blinking visible light laser beam.
 21. The device ofclaim 1, integrated with a microscope.
 22. The device of claim 1,integrated with an aberrometer configured to measure refractiveproperties of the eye.